JP2009044666A - Camera equipped with liquid crystal lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To overcome the problem in which display of a screen with a deteriorated quality of image occurs in a transient state using a liquid crystal lens. <P>SOLUTION: A camera includes both a curved lens at least one surface of which is curved and a liquid crystal lens, a switch for setting a normal photographing mode or a macro photographing mode, a signal processing circuit for processing an image signal entered through the lenses, an image recording register for recording an output of the signal processing circuit, a specified image preparing means for preparing a specified image, and a display monitor for displaying the content of the image recording register or the specified image. When the normal photographing mode is set by the switch, the liquid crystal lens is brought into an off state, and when the macro photographing mode is set by the switch, the liquid crystal lens is brought into an on state. Responding to a change of the photographing modes, the specified image is displayed on the display monitor. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a camera provided with a liquid crystal lens, and more particularly to a display when the liquid crystal lens is turned on.

Conventionally, with a camera equipped with a macro shooting mechanism, maintaining the image quality when shifting from the normal shooting mode to the macro shooting mode, which is close-up shooting, has been a major problem.
For example, there is a proposal to increase the gain of a circuit that amplifies an image signal at the time of macro photography, while making it easy to focus by narrowing the aperture, that is, to improve the image quality by preventing defocusing (see, for example, Patent Document 1)) .

However, the situation is different for cameras incorporated in small portable devices such as mobile phones.
In a camera incorporated in such a small device, it is necessary to reduce the mechanical size. Therefore, it is desirable not to use an aperture mechanism with a variable aperture amount as well as an autofocus mechanism and a zoom mechanism. On the other hand, in addition to the normal shooting mode that is the normal long-distance shooting mode, the macro shooting mode that is the close-up mode is necessary.

For this reason, there is an idea of using a liquid crystal lens in addition to a normal curved lens having at least one curved surface and fixing the focus in the normal shooting mode and the macro shooting mode.
In other words, the liquid crystal lens is always placed in the photographing optical path, and in the normal photographing mode that is a long-distance photographing mode, the liquid crystal lens is turned off to increase the focal length of the lens system, and in the macro photographing mode that is a close-up mode Is a method in which the liquid crystal lens is turned on to reduce the focal length of the lens system.

FIG. 8 is a diagram showing an example of the liquid crystal lens 10.
The liquid crystal lens 10 is configured by sandwiching a liquid crystal material between transparent flat substrates 104 and 106, and a concentric transparent electrode 100 hatched in FIG. 7 is formed on the liquid crystal material side of the flat substrate 104. A common electrode is formed on the entire surface of the flat substrate 106 so as to cover the transparent electrode 100 on the liquid crystal material side.

  The problem is that the extraction electrode 102 for applying a driving voltage to the concentric transparent electrode 100, and the light is also modulated in the extraction electrode portion 102, so that the image quality is deteriorated. In addition, since the response of the liquid crystal is slow, it may take time to respond normally in the transitional state at the time of switching. As described above, there is a problem in that the image quality deterioration when the shooting mode is switched gives the user a sense of incongruity, and the reliability of the camera is lost.

Although there is a method in which transparent electrodes are multilayered to eliminate such an adverse effect of the extraction electrode, the cost increase due to the increase in the number of processes is large and difficult to realize.
In addition, in the following drawings, the same number is attached | subjected to the same member and description is abbreviate | omitted.

JP 05-066644

  The problem to be solved is that a screen with degraded image quality is displayed in a transient state using a liquid crystal lens.

  A camera equipped with a liquid crystal lens according to the present invention captures through both the curved lens having at least one curved surface and a liquid crystal lens, a switch for setting a normal shooting mode or a macro shooting mode, and the lens. A signal processing circuit for processing an image signal, an image recording register for recording the output of the signal processing circuit, a specific image generating means for generating a specific image, and a display monitor for displaying the contents of the image recording register or the specific image When the normal shooting mode is set by the setting switch, the liquid crystal lens is turned off. When the macro shooting mode is set by the setting switch, the liquid crystal lens is turned on. When the photographing mode is changed, the specific image is displayed on the display monitor.

  The camera equipped with the liquid crystal lens according to the present invention is configured such that the signal processing circuit can select a plurality of signal processing methods, and when the setting switch is switched, the signal processing method is selected again. The specific image is displayed on the display monitor.

  Further, the camera equipped with the liquid crystal lens according to the present invention is characterized in that in the signal processing method selected when the liquid crystal lens is ON, the output luminance level is processed to be lower than the input luminance level.

  In addition, a camera having a liquid crystal lens according to the present invention has a timer function, and displays the specific image for a time determined by the timer function.

  It is possible to clearly notify the user that the shooting mode has been switched, and it is possible to obscure the white blurring and the transient state that occur during the switching period.

At least one of a curved lens having a curved surface and a liquid crystal lens, a switch for setting a normal shooting mode or a macro shooting mode, a signal processing circuit for processing an image signal captured through the lens, An image recording register for recording the output of the signal processing circuit, a specific image creating means for creating a specific image, and the contents of the image recording register or a display monitor for displaying the specific image, and normal shooting by the setting switch When the mode is set, the liquid crystal lens is turned off. When the macro shooting mode is set by the setting switch, the liquid crystal lens is turned on. When the shooting mode is changed, the display monitor is turned on. The specific image is displayed.
Hereinafter, the present invention will be described based on examples.

FIG. 1 is a diagram schematically showing an image capturing system of a camera 98 having a liquid crystal lens according to the present invention.
The light 13 emitted from the subject 11 shown in FIG. 1 is a liquid crystal lens 10, a lens barrel 12 having a curved lens in which at least one is a commonly used optical lens, an IR cut filter 14, and a sensor that is an image sensor. 16 through the camera.
That is, in the camera of the present invention, the liquid crystal lens 10 is always placed in the photographing optical path.
The order in which the liquid crystal lens 10, the lens barrel 12, and the IR cut filter 14 are arranged is not limited to that shown in FIG. 1, and can be designed in any order.

FIG. 2 is a block diagram of a camera 98 having a liquid crystal lens according to the present invention.
In FIG. 2, light from a subject passes through a liquid crystal lens 10, a curved lens 18, and various photographing mechanisms 20, and forms an image on a surface of an image pickup device 22 such as a CCD or CMOS sensor and is photoelectrically converted. The image pickup signal output from the image pickup device 22 is converted into a predetermined recording output by the signal processing circuit 24 and recorded in the image recording register 26. The contents of the image recording register 26 are displayed on the display monitor 28 in accordance with an instruction from the CPU 32. Is displayed. The signal processing circuit 24 has an image processing function such as amplifying the imaging signal.

  The setting switch 30 is used to set the normal shooting mode or the macro shooting mode. For example, the bi-stable switch is set to the normal shooting mode for long-distance shooting in one stable state, and to the short-distance shooting in the other stable state. Macro shooting mode can be set. A bar code reading state described later can also be included in the macro shooting mode. Further, the setting switch 30 can be a tristable switch, and the third stable state can be set to the bar code reading mode, or a plurality of switches can be provided in the setting switch 30 to be used exclusively for setting the bar code reading mode. . The CPU 32 controls the entire camera system by looking at the state of each block.

Further, the camera 98 having the liquid crystal lens according to the present invention has a specific image creating means 27 for creating a specific image, and causes the display monitor 28 to display an image created by the specific image creating means 27 according to a command from the CPU 32. The specific image is not an image photographed through the lens system, but is a screen generated in the camera system and is understood by the user as an image that is not an output screen from the camera. Such a specific image is displayed when the shooting mode is switched by the setting switch 30, and prevents a screen with a deteriorated image quality from being displayed in a transient state where the liquid crystal lens 10 is switched on and off. The user is clearly informed that has been switched.
Of course, the CPU 32 can instruct the display monitor 28 to display the currently selected photographing mode. The release button 34 is a so-called shutter, and when the button 34 is operated, the CPU 32 captures an image and instructs display on the display monitor 28.

  That is, the camera 98 having the liquid crystal lens of FIG. 2 includes both the curved lens 18 and the liquid crystal lens 10 having at least one curved surface, the switch 30 for setting the normal photographing mode or the macro photographing mode, A signal processing circuit 24 for processing an image signal captured through the lens, a register 26 for recording the output of the signal processing circuit, a specific image generating means 27 for generating a specific image, and the contents of the register 26 or displaying the specific image Display monitor.

  It should be noted here that the camera 98 equipped with the liquid crystal lens according to the present invention is intended to be miniaturized, and therefore the autofocus mechanism can be removed. For example, instead of the autofocus mechanism, at least two shooting modes, a normal shooting mode that is a long-distance shooting mode, and a macro shooting mode that is a close-up mode are provided, and a fixed focus method is adopted for at least the curved lens 18 in each mode. It is possible that In the macro photography mode, the liquid crystal lens 10 is turned on to adjust the focus to a short distance. That is, in the normal photographing mode and the macro photographing mode, the focal length of the curved lens 18 is made equal to reduce the size, and the focal length is changed only by turning the liquid crystal lens 10 ON or OFF.

FIG. 3 is a diagram showing a configuration example of the signal processing circuit 24 shown in FIG.
In FIG. 3, the signal processing circuit 24 has an image processing register 46, and the image processing register 46 selects one of a plurality of N signal processing methods 36, 38, 40, 42 by a selection circuit 44. Read. For example, γ correction of a video signal is a kind of this signal processing method. Which signal processing method is selected depends on an instruction from the CPU 32.
That is, the signal processing circuit 24 is configured to be able to select a plurality of signal processing methods.

FIG. 4 is a flowchart showing an example of a control method of the camera 98 having the liquid crystal lens according to the present invention. The control method according to the present invention will be described with reference to FIG.
In FIG. 4, when the camera is turned on at 48, initialization is performed at 50. Here, for example, the normal photographing mode is set and the liquid crystal lens is turned off.
Next, at 52, the setting switch 30 is checked to see if the shooting mode has been switched.
If switched, the process proceeds to 51 to display a specific image and switch the ON / OFF state of the liquid crystal lens 10, and the signal processing method is selected at 54, that is, the signal processing methods 36, 38, 40, shown in FIG. One of 42 that is suitable for the switched shooting mode is selected.

If not switched, the process proceeds to 55, and the ON / OFF state of the liquid crystal lens 10 is not changed, that is, maintained, and the signal processing method is also maintained at 55 at the previous state.
After the signal processing method is determined in 54 or 57, the signal processing method selected in the signal processing circuit 24 shown in FIG. 3 is written in the image processing register 46, and the image signal processed by the processing method is an image. It is written in the recording register 26. At 59, the contents of the image recording register 26 are displayed on the display monitor 28.

Therefore, even if the shooting mode can be switched, after the image is processed according to the signal processing method for the shooting mode, the image is displayed on the display monitor, so that the display image quality degradation or the transient state that occurs during the switching period is inconspicuous. It is possible.
Since the liquid crystal has a problem that the response is slow, for example, after changing the signal processing method at 54, a timer is provided at 61, and it continues to display the specific image for a certain period of time.
In such a transient response of the liquid crystal and the timing at the time of register switching, an image different from the actual image is displayed on the display monitor. During this time, it is not possible to display a specific image on the display monitor to remove the user's uncomfortable feeling. is important.
With this configuration, it is possible to reliably remove the influence of the transient response of the liquid crystal.
A reasonable time length of the timer is about 0.5 to 2 seconds.

Next, at 56, it is monitored whether the shutter release button 34 has been operated. If it has been operated, an image is captured via the liquid crystal lens 10, the curved lens 18, the photographing mechanism 20, and the image sensor 22 at 58, and the operation proceeds to 60. The captured image signal is subjected to image signal processing by the signal processing circuit 24, the processed image signal is recorded in the image recording register 26 at 62, and the contents of the image recording register 26 are displayed on the display monitor 28 at 64. Return to 52.
If the release button 34 is not operated, the process returns to 52.
As described above, since the control of the camera according to the present invention stands by in the loop shown in FIG. 4, when the photographing mode is switched by the setting switch 30, the liquid crystal lens is immediately switched on and off, and the signal processing method is also switched. And written in the image processing register 46.

The camera 98 having the liquid crystal lens according to the present invention turns off the liquid crystal lens 10 when the normal photographing mode is set by the setting switch 30 and turns on the liquid crystal lens 10 when the macro photographing mode is set. It is said.
When macro photography is set, the liquid crystal lens is turned on and the signal processing method is reread by the image register 46, and a specific image is displayed during that time, so that a change in image quality due to the liquid crystal lens may be displayed. And the occurrence of a sense of incongruity can be suppressed.
The signal processing circuit 24 is configured to be able to select a plurality of signal processing methods, and is configured to reselect the signal processing method when the setting switch 30 is switched and the photographing mode is changed.

  When the liquid crystal lens is used, the light is also modulated in the extraction electrode portion 102 as described with reference to FIG. However, in the camera 98 equipped with the liquid crystal lens according to the present invention, the signal processing circuit 24 reselects the signal processing method for the liquid crystal lens before displaying the image obtained through the liquid crystal lens 10, and during that time the specific image is selected. Since the specific image created by the creation unit 27 is displayed on the display monitor 28, it is possible to prevent the deteriorated image from being displayed on the display monitor 28, and to avoid a situation in which an uncomfortable feeling is caused.

FIG. 9 is another example of a block diagram of a camera 98 having a liquid crystal lens according to the present invention. The block diagram of FIG. 9 is different from that of FIG. 2 in that a temperature sensor 31 is provided.
In FIG. 9, the output of the temperature sensor 31 is given to the CPU 32. Since the liquid crystal lens has a large temperature dependence of response speed, the timer time is made variable according to the temperature detected by the temperature sensor 31.
Of course, the CPU 31 has a timer function.

FIG. 5 shows a first embodiment of the signal processing system shown in FIG. 3, in which the liquid crystal lens 10 takes measures against image deterioration when the liquid crystal lens 10 is ON.
In FIG. 5, the horizontal axis represents input luminance, and the vertical axis represents output luminance. Bw shown on the horizontal axis indicates the width from black to white that the camera can actually recognize.
The dotted line 66 connects the points where the input luminance and the output luminance are equal, but the curve of the signal processing result indicated by the thick line 68 is shifted in a direction where the luminance of the output signal is smaller than that of the dotted line 66.
Such a process is a problem specific to the case of using a liquid crystal lens that increases the output brightness over the input brightness and increases the resolution of the black part, which is the reverse of the so-called night mode, and prevents image deterioration due to the liquid crystal lens. .
By switching to such a processing method, it is possible to remove the whitishness of an image that has become whitish by using a liquid crystal lens.

On the other hand, signal processing when the liquid crystal lens 10 is OFF performs so-called known γ correction. The signal processing for image degradation countermeasures shown in FIG. 5 is preferably a combination of gamma correction and image degradation countermeasures, and the specific conversion values depend on the characteristics of the curved lens, liquid crystal lens, etc. that are actually employed.
That is, the camera equipped with the liquid crystal lens of the present invention is configured to select at least a different signal processing method when the liquid crystal lens is on and off, and in the signal processing method selected when the liquid crystal lens is on. Are processed so that the output luminance level becomes lower than the input luminance level.

FIG. 6 shows a second embodiment of the signal processing system in which a measure for accurately reading a barcode is applied. Since the barcode reading is performed in the macro shooting mode, the signal processing method shown in FIG. 6 is selected in the macro shooting mode.
In FIG. 6, as in FIG. 5, the horizontal axis represents input luminance, the vertical axis represents output luminance, Bw on the horizontal axis represents the width from black to white that can be actually recognized by the camera, and the dotted line 66 represents input. The points where the luminance and output luminance are equal are connected.
In the signal processing method shown in FIG. 6, a threshold value Bth of input luminance is provided, and when the input luminance is higher than the threshold value Bth, the output luminance is a thick line 72 close to the white level, and the input luminance is higher than the threshold value Bth. Is low, the output luminance is processed to be a thick line 70 close to the black level.

By processing the image signal in this way, it is possible to accurately read a barcode represented by binary values of white and black. This signal processing method is particularly effective when used in the barcode reading mode.
In the barcode reading mode, the liquid crystal lens 10 is turned on and the focus is adjusted to a short distance.
It is also effective to provide a known edge enhancement function.

  Furthermore, it is also effective to increase the accuracy of barcode reading by converting an image signal handled in normal color into a monochrome signal of only black and white. Of course, such a conversion method can be provided in the signal processing circuit 24 as one of the signal processing methods.

  In recent years, barcodes have become widespread, and in particular, QR codes in which barcodes are two-dimensionally developed have appeared. Barcodes cannot be read accurately with cameras for small portable devices, and in particular, QR codes have many reading errors. However, these problems can be solved by using the signal processing method described in FIG.

FIG. 7 is a diagram showing an example of a specific image created by the specific image creating means 27 shown in FIG.
In FIG. 7, (a) is a blank image with a white screen, (b) is a blank image with a black screen, (c) is “Please wait”, and (d) is a comment display image of “Switching”. .
Of course, it is possible and effective to display the currently set shooting mode in such a specific image.
In this way, the specific image is clearly not an image taken through the lens system, but an image that can be seen as a screen generated in the camera system, and is displayed when there is a possibility that the output screen may be disturbed by changing the settings inside the camera. The

As described above, according to the present invention, it is possible to clearly notify the user that the shooting mode has been switched, and it is possible to make the display image quality degradation that occurs during the switching period inconspicuous.
In the present specification, the case where a liquid crystal lens is used has been described. However, the same effect can be obtained by using a liquid lens instead of the liquid crystal lens.

It is the figure which showed typically the image capture system of the camera provided with the liquid crystal lens by this invention. It is a block diagram of the camera provided with the liquid-crystal lens by this invention. It is the figure which showed the structural example of the signal processing circuit. 5 is a flowchart illustrating an example of a control method of a camera including a liquid crystal lens according to the present invention. It is a 1st Example of a signal processing system. It is a 2nd Example of a signal processing system. It is the figure which showed the Example of the specific image. It is the figure which showed the example of the liquid crystal lens. It is another example of the block diagram of the camera provided with the liquid crystal lens by this invention.

Explanation of symbols

18 curved lens 10 liquid crystal lens 30 setting switch 24 signal processing circuit 26 image recording register 27 specific image creating means 28 display monitor

Claims (4)

A curved lens having at least one curved surface and a liquid crystal lens;
A switch for setting between normal shooting mode and macro shooting mode,
A signal processing circuit for processing an image signal captured through the lens;
An image recording register for recording the output of the signal processing circuit;
Specific image creation means for creating a specific image;
A display monitor for displaying the contents of the image recording register or the specific image;
When the normal shooting mode is set by the setting switch, the liquid crystal lens is turned off,
When the macro shooting mode is set by the setting switch, the liquid crystal lens is turned on,
A camera provided with a liquid crystal lens, wherein the specific image is displayed on the display monitor when the photographing mode is changed. The signal processing circuit is configured to be able to select a plurality of signal processing methods,
When the setting switch is switched, the signal processing method is selected again.
2. The camera with a liquid crystal lens according to claim 1, wherein the specific image is displayed on the display monitor at the time of switching.   4. The camera with a liquid crystal lens according to claim 3, wherein the signal processing method selected when the liquid crystal lens is ON is processed so that the output luminance level is lower than the input luminance level. 2. The camera with a liquid crystal lens according to claim 1, further comprising a timer function, wherein the specific image is displayed for a time determined by the timer function.

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